The first poster congratulating Rory McIlroy was up by 6am yesterday in his home town of Holywood, tacked up by Margaret Hamilton in the window of the Oxfam shop in the High Street.

Mrs Hamilton was proud to be the first but like the rest of the County Down town, was even prouder of Rory. "Everybody's delighted," she said, radiating unfeigned enjoyment. "It's marvellous, just brilliant – how wonderful."

Further down the High Street Valerie Skinner of Skinner's home bakery was also quick off the mark, downloading a picture of Rory off the internet, arms raised in triumph. She then imprinted this on a hundred buns. By mid-morning they were all gone.

Meanwhile Holywood Golf Club started taking bookings for the Rory McIlroy golf classic in August. "The time-sheet went live this morning," said a club official, "and it was full within 10 minutes. The whole thing's booked solid."

In Holywood yesterday, none of this smacked of a rush to clamber on to a Rory bandwagon and exploit his success. Rather, this generally good-natured town projected genuine happiness and pride at his extraordinary success.

This is mostly due to his talents but in local terms it is also because of his personality and his family. "He's been very good to the juveniles," they say at the club. "He still comes down and chats to the people as normal and he has made very generous donations."

And the McIlroy family is everywhere held in high regard. "Lovely people, very down to earth, nice people," said Mrs Hamilton. "A good family," said a jogger near the golf course. "Very good – couldn't say a bad word against them."

Even a High Street bookie was chuffed with the result, even though many locals had placed bets on Rory. "It's great, great, I'm pleased for him," said Stephen Forde. "There are always lots of bets on him. I think he was 20 to 1 for the next tournament but he's now 5 to 1, so the bookies are scared of him."

Like the McIlroy family and indeed Holywood town itself, the clubhouse is modest and informal. Veteran Eddie Harper, who ran the club's juvenile committee for 23 years, gestured around the lounge and reminisced: "I've known Rory since he was born. When he was three he used to be hitting plastic golf balls round this floor. He was so good, but he was so frustrated at not getting out to play on the course."

For safety reasons children were not usually allowed out until the age of 10, but Rory was so "spectacularly keen" that the club looked on him as a special case.

Eddie recalled: "I got the club council to agree to interview him. He was seven. He was nicely dressed for his interview and he was very polite. He was very mature for his age and he assured us that he knew the rules and wouldn't be any trouble to anybody. So we got him in."

In those days Rory's father Gerry worked in the lounge as bar manager. One of the reasons why Gerry and his wife Rosie are locally held in high regard is because the town is aware of sacrifices they made in the early, expensive, days of their son's career.

Money had to be found for equipment, coaching, travel and other expenses. "There was very little money in those days," Eddie recalled. "As well as working here Gerry was doing stints in various other bars while Rosie was working too, on night shifts."

The same lounge, where Gerry served drinks as toddler Rory developed his putting technique, was packed in the early hours yesterday, locals erupting when he won the US Open.

Rory has been properly appreciative to his folks. During the US Open presentation ceremony he called across to his father: "Happy Father's day – this one's for you." His dad later emotionally responded: "On Father's day, what a present."

The Holywood club is festooned with photographs and mementoes of Rory. An old letter of his in an earnest schoolboy hand, thanking staff and members for their help and encouragement, has been reverently framed. A clipping from a local paper proclaims: "Watch out Tiger Woods! Hotfoot golfer Rory McIlroy is out to steal your thunder." The Holywood boy was aged nine at the time.

Now a space is doubtless being reserved for a large photograph of him with his trophy, with other spaces earmarked for the years ahead.

By late morning yesterday not quite everyone in Holywood was basking in the general warm glow generated by Rory's success. At a hole close to the clubhouse a player in his 20s could be seen making several unsuccessful attempts to chip his ball out of a bunker.

Eventually he picked the ball out of the sand and simply threw it on to the green. The comments he muttered to himself, though inaudible, presumably expressed the sentiment that not everyone can be a Rory McIlroy.

Finding the green

After humble beginnings in Holywood, Rory McIlroy has already earned a small fortune but, at his age and with his natural talent and temperament, the man they're calling the new Tiger Woods is destined to make much, much more.

The golfer could see his sponsorship deals, already reported to be worth £6m a year, double as big brands pitch for his face and name. If he consolidates his success to climb up the world rankings (he is fourth now) he has the potential to give Woods a run for his money. Woods, his recent trouble notwithstanding, has amassed an estimated billion pounds from deals with brands such as Nike and remains the biggest earner in sport.

McIlroy's sponsors include Titleist and Oakley, which may find themselves paying more to get their names on the golfer as his agents get wise to his new-found fame.

The McIlroy effect may extend to the courses on which he honed his talents. Local authorities are already thinking of how to build on his triumph. This could be a golden marketing opportunity for a region where tourism has suffered lately. Golf tourism is big business: the Government hopes a major tournament could be hosted by 2016.